“It is tough for him,” his teammate and fellow former Celtic Paul Pierce told the Brooklyn media Wednesday.

“We had a chance to see him get out on the court and do some extra stuff [on Wednesday before beating Memphis]. But he is a competitor. He hates to sit out. The good thing is we need him to get his rest so he can come back full strength.”

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Rookie Mason Plumlee has been starting in place of Garnett, who missed one game in November with a sprained ankle and has sat out in several others to rest, as the team wants him ready for the postseason.

As of Thursday, the Nets (30-29) were in sixth place in the Eastern Conference standings, having won four straight and five of their last six.

In an up-and-down and injury-plagued season, Garnett has struggled to find his form, averaging career-lows in points (6.7) and rebounds (6.7).

Garnett made an emotional return to Boston Jan. 26, when he and Pierce came back to TD Garden for the first time since they were traded last summer.

Both players were honored with video tributes and long standing ovations.

Garnett played for six seasons in Boston and won a title with the Celtics in 2008.

Friday will also mark the return of Jason Collins, the former Celtics center who was traded to Washington in 2013.

Collins joined the Nets this season, becoming the first openly gay player in one of America’s major sports leagues. He also signed a second 10-day contract with the Nets.

Because Collins played with Garnett and Pierce, he said he believes “a lot of those emotions will still be there” Friday night.

“But it’s good that [Pierce and Garnett] already have made the trip there. I, too, being a former Celtic, I’m looking forward to going back and seeing a bunch of people there,’’ Collins said. “So it’ll be one of those things where you really have to focus on the game when the ball gets tipped up in the air.”

One-of-a-kind gift

After the Celtics’ loss Wednesday, Rajon Rondo signed the sneakers he wore during the game and made sure they were delivered to 12-year-old Louis Corbett.

Receiving such a gift from his favorite player capped off a one-of-a-kind night for Corbett, who had come all the way from New Zealand to see the Celtics play.

With help from Warren Casey, the CEO of a Boston-based software firm, and from Corinne Grousbeck, wife of Celtics co-owner Wyc Grousbeck, the team helped fund a trip for Corbett and family members after learning he has a rare degenerative eye disease that is causing him to lose his eyesight.

Corbett had created a “visual bucket list” of things he’d like to see before his sight is gone, including the Grand Canyon, Empire State Building, and Niagara Falls.

But at the very top was his wish to see the Celtics, his favorite team, in person.

The Celtics gave Corbett the VIP treatment. He met with Rondo, other players and Celtics coach Brad Stevens before the game. He also sat courtside and was honored during an early timeout.

“It was very exciting to meet him,” Rondo said. “What he’s going through, he still has a smile on his face. He’s very humble. Because we all do what we love to do for a living and you never know, at any moment, it could be taken from you. You just try not to take anything for granted.”

Like Rondo, Jeff Green also gave Corbett a pair of game-worn sneakers.

“We can get down over the little things and then you have a kid who is about to have a surgery in a couple of weeks who is going to be blind and right now he is enjoying one day at a time,” Green said. “Sometimes it puts life in perspective.”

Stevens said he wished his team had played better for Corbett, but he was proud of the Celtics for stepping up to help give him a special night.

“I just think it’s the way we should be. It’s the way an organization should be. You should give back to community,” said Stevens. “I don’t know that you should necessarily be applauded for it. I think you should just do it. Stories like that are uplifting to all of us, and I hope that he had a great night even though we didn’t play well.”